Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 20 May 2022 10:58:53 +0200
From:   Joerg Roedel <joro@8bytes.org>
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        iommu@lists.linux-foundation.org, jon.grimm@amd.com,
        linux-kernel@vger.kernel.org, vasant.hegde@amd.com
Subject: Re: [PATCH v2] iommu/amd: Set translation valid bit only when IO
 page tables are in used
Message-ID: <YodYTZzSd9fZucLT@8bytes.org>
References: <20220509074815.11881-1-suravee.suthikulpanit@amd.com>
 <Yn5YIfzmerwAM30M@8bytes.org>
 <1dfaf07e-040e-848b-db7c-86a107fd5cb3@amd.com>
 <YodMvV/8eii4KCLg@8bytes.org>
 <794e13dd-8eae-481d-711d-b5462fdbfb18@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <794e13dd-8eae-481d-711d-b5462fdbfb18@arm.com>
Precedence: bulk

On Fri, May 20, 2022 at 09:54:51AM +0100, Robin Murphy wrote:
> The .def_domain type op already allows drivers to do exactly this sort of
> override. You could also conditionally reject IOMMU_DOMAIN_PASSTHROUGH in
> .domain_alloc for good measure, provided that (for now at least*) SNP is a
> global thing rather than per-instance.

Yeah, that could work. I am just not sure the IOMMU core behaves well in
all situations when allocation IOMMU_DOMAIN_PASSTHROUGH suddenly starts
to fail. I would feel better if this is checked and tested :)

Regards,

	Joerg